1. Field of the Invention
The present invention relates to a microorganism monitoring apparatus, and more particularly to an apparatus for directly monitoring microorganisms present in a liquid.
2. Description of the Prior Art
In a microbiological process such as one wherein a waste water such as sewage is treated by bacteria or wherein an antibiotic substance is produced by fermentation, it is necessary to monitor the state of the microorganism (in the former, the state of bacteria flocs and the species of protozoa, metazoa; in the latter, the state of molds) in order to learn the treatment condition of the waste water or the stage of fermentation. Conventionally, this observation is performed by microscopic examination of a sample taken from the waste water or the fermented liquid. Obviously, however, it is troublesome to take such samples and to prepare specimens for microscopic observation. Also, in the case of microscopic observation, there is the possibility that the state of the microorganism actually observed may not be the same as those in the liquid in the vessel because, for example, aggregations of the microorganisms may be broken up when the specimen is prepared.
In view of the drawbacks of the conventional method mentioned above, a microorganism monitoring apparatus by which the microorganism present in the liquid contained in the vessel can be directly observed and monitored has previously been proposed and is disclosed, for example, in JAPANESE PATENT PUBLIC DISCLOSURES No. 52(1977)-89942 and No. 52(1977)-99839 which were filed on Jan. 23, 1976 and Feb. 17, 1976, respectively.
JAPANESE PATENT PUBLIC DISCLOSURE No. 52(1977)-89942 discloses a microorganism monitoring apparatus comprising a cylindrical housing extending through a wall of the vessel and having a window glass mounted on its inner end so that one face of the window glass is adapted to be contacted with the liquid in the vessel, an optical magnifying system disposed within the cylindrical housing and having an objective lens which is opposed to the other face of the window glass, a TV camera provided opposite to an eye piece of the optical magnifying system, a monitor TV associated with the TV camera, and a strobo light source having a light guide which extends through the wall of the vessel into the liquid so that an end face of the light guide is directed to the one face of the window glass. In this apparatus, although the microorganisms are in motion in the liquid contained in the vessel, a static image of the microorganisms which pass through the space between the end face of the light guide and the one face of the window glass can be displayed on the monitor TV due to use of the strobo flash emitted from the strobo light source. In this way, it is possible to directly observe and monitor the microorganisms in motion in the liquid contained in the vessel. However, in this apparatus, it is impossible to continuously observe and monitor the microorganisms over time because the microorganism cannot be captured in the space between the end face of the light guide and the one face of the window glass. Also, when the end face of the light guide and/or the one face of the window glass are smudged with, for example, dregs, dirt or the like included in the liquid, it is impossible to obtain a clear image on the monitor TV.
JAPANESE PATENT PUBLIC DISCLOSURE No. 52(1977)-99839 discloses a microorganism monitoring apparatus comprising a first closed housing which is adapted to be submerged in the liquid contained in the vessel, an optical magnifying system provided within the first closed housing so that an objective lens thereof is adapted to be directly contacted with the liquid, a TV camera provided within the first closed housing and associated with the optical magnifying system, a second closed housing having a window glass opposed to the objective lens of the optical magnifying system and movably supported by the first closed housing so that the space between the window glass and the objective lens can be adjusted, and a strobo light source disposed within the second closed housing so that it is opposed to the window glass. Said DISCLOSURE No. 52(1977)-99839 also discloses a microorganism monitoring apparatus comprising a cylindrical housing integrally formed in a wall of the vessel containing the liquid, an optical magnifying system provided within the cylindrical housing so that an objective lens thereof is adapted to be directly contacted with the liquid, a TV camera associated with the optical magnifying system, a strobo light source having a light guide which extends through the wall of the vessel into the liquid so that an end face of the light guide is directed to the objective lens, and the strobo light source movable together with the light guide so that the space between the end face of the light guide and the objective lens of the optical magnifying system can be adjusted. In these apparatuses, the space between the window glass and the objective lens or the end face of the light guide and the objective lens is narrowed down so that the microorganisms passing therethrough are temporarily captured in the space during the passage, whereby it is possible to observe and monitor the microorganism in a static condition in spite of the fact that the microorganisms are in motion in the liquid contained in the vessel. However, in these apparatuses, it is also impossible to prevent the window glass of the second closed housing, the end face of the light guide and/or the objective lenses from being smudged with dregs, dirt or the like included in the liquid. Of course, when they are smudged with the dregs, dirt or the like, it is impossible to obtain a clear image on the monitor TV.